Ueno Hironori, Iwataki Yoshinori, Numata Osamu
Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572.
J Biochem. 2006 Oct;140(4):525-33. doi: 10.1093/jb/mvj182. Epub 2006 Aug 26.
Calmodulin (CaM) is an axonemal component. To examine the pathway of Ca(2+)/CaM signaling in cilia, using Ca(2+)/CaM-affinity column, we identified seven Ca(2+)/CaM-associated proteins from a crude dynein fraction and isolated 62 kDa (p62) and 66 kDa (p66) Ca(2+)/CaM-associated proteins in Tetrahymena cilia. The amino acid sequences deduced from the p62 and p66 cDNA sequences suggested that these proteins were similar to Chlamydomonas radial spoke proteins 4 and 6 (RSP4 and RSP6), components of the radial spoke head, and sea urchin sperm p63, which is a homologue of RSP4/6, and isolated as a key component that affect flagellar bending patterns. Although p62 and p66 do not have a conventional CaM-binding site, those have consecutive sequences which showed high normalized scores (>or= 5) from a CaM target database. These consecutive sequences were also found in RSP4, RSP6, and p63. These radial spoke heads proteins have a high similarity region composed of 15 amino acids between the five proteins. Immunoelectron microscopy using anti-CaM antibody showed that CaM was localized along the outer edge of the curved central pair microtubules in axoneme. Therefore, it is possible that the interaction between Ca(2+)/CaM and radial spoke head control axonemal curvature in the ciliary and flagellar waveform.
钙调蛋白（CaM）是轴丝的一个组成部分。为了研究纤毛中Ca(2+)/CaM信号传导途径，我们使用Ca(2+)/CaM亲和柱，从粗制动力蛋白组分中鉴定出7种Ca(2+)/CaM相关蛋白，并在嗜热四膜虫纤毛中分离出62 kDa（p62）和66 kDa（p66）的Ca(2+)/CaM相关蛋白。从p62和p66 cDNA序列推导的氨基酸序列表明，这些蛋白与衣藻辐射辐条蛋白4和6（RSP4和RSP6）、辐射辐条头部的组成成分以及海胆精子p63相似，p63是RSP4/6的同源物，作为影响鞭毛弯曲模式的关键成分被分离出来。虽然p62和p66没有传统的CaM结合位点，但它们具有连续序列，从CaM靶数据库中显示出高标准化分数（≥5）。这些连续序列也在RSP4、RSP6和p63中发现。这五种蛋白的这些辐射辐条头部蛋白有一个由15个氨基酸组成的高度相似区域。使用抗CaM抗体的免疫电子显微镜显示，CaM定位于轴丝中弯曲的中央微管对的外边缘。因此，Ca(2+)/CaM与辐射辐条头部之间的相互作用有可能控制纤毛和鞭毛波形中的轴丝曲率。
